Isoprene is polymerized in the production of synthetic rubber. The physical properties of synthetic rubber are highly dependent on the underlying microstructure. Polymer chains of mixed microstructure results in synthetic rubber of lower quality than synthetic rubbers of a single microstructure repeated in an orderly fashion. Synthetic rubber producers prefer high-purity isoprene since it produces a synthetic rubber with a highly uniform microstructure and with desirable physical properties.
Carbon disulfide, (“CS2”) is often present in C5 naphtha used to make isoprene. CS2 may poison catalysts used to facilitate removal of other hydrocarbon impurities in the isoprene or Ziegler catalysts used in the polymerization process. Unfortunately, CS2 and isoprene have similar boiling points, thus it is difficult to remove CS2 through distillation. Thus, scavengers comprising polyamines are frequently used in isoprene production to react with the CS2 and facilitate its removal from the isoprene.